Images: Implement internal DIB image plugin.

For use for clipboard/DnD operations on Windows by its
Lighthouse plugin (to prevent having to export qt_read_dib(),
qt_write_dib()).

Change-Id: I79e69bf7cecb16cc47ea29de6805fc52e4df1007
Reviewed-on: http://codereview.qt.nokia.com/1714
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oliver Wolff <oliver.wolff@nokia.com>

src/gui/image/qbmphandler.cpp

@@ -646,11 +646,16 @@ bool qt_read_dib(QDataStream &s, QImage &image)
     return read_dib_body(s, bi, -1, -BMP_FILEHDR_SIZE, image);
 }
 
-QBmpHandler::QBmpHandler()
-    : state(Ready)
+QBmpHandler::QBmpHandler(InternalFormat fmt) :
+    m_format(fmt), state(Ready)
 {
 }
 
+QByteArray QBmpHandler::formatName() const
+{
+    return m_format == BmpFormat ? "bmp" : "dib";
+}
+
 bool QBmpHandler::readHeader()
 {
     state = Error;
@@ -663,7 +668,7 @@ bool QBmpHandler::readHeader()
     s.setByteOrder(QDataStream::LittleEndian);
 
     // read BMP file header
-    if (!read_dib_fileheader(s, fileHeader))
+    if (m_format == BmpFormat && !read_dib_fileheader(s, fileHeader))
         return false;
 
     // read BMP info header
@@ -676,11 +681,11 @@ bool QBmpHandler::readHeader()
 
 bool QBmpHandler::canRead() const
 {
-    if (state == Ready && !canRead(device()))
+    if (m_format == BmpFormat && state == Ready && !canRead(device()))
         return false;
 
     if (state != Error) {
-        setFormat("bmp");
+        setFormat(formatName());
         return true;
     }
 
@@ -732,6 +737,12 @@ bool QBmpHandler::read(QImage *image)
 
 bool QBmpHandler::write(const QImage &img)
 {
+    if (m_format == DibFormat) {
+        QDataStream dibStream(device());
+        dibStream.setByteOrder(QDataStream::LittleEndian); // Intel byte order
+        return qt_write_dib(dibStream, img);
+    }
+
     QImage image;
     switch (img.format()) {
     case QImage::Format_ARGB8565_Premultiplied:
@@ -829,7 +840,7 @@ void QBmpHandler::setOption(ImageOption option, const QVariant &value)
 
 QByteArray QBmpHandler::name() const
 {
-    return "bmp";
+    return formatName();
 }
 
 QT_END_NAMESPACE

src/gui/image/qbmphandler_p.h

@@ -81,10 +81,20 @@ struct BMP_INFOHDR {                     // BMP information header
     qint32  biClrImportant;              // number of important colors
 };
 
+// BMP-Handler, which is also able to read and write the DIB
+// (Device-Independent-Bitmap) format used internally in the Windows operating
+// system for OLE/clipboard operations. DIB is a subset of BMP (without file
+// header). The Windows-Lighthouse plugin accesses the DIB-functionality.
+
 class QBmpHandler : public QImageIOHandler
 {
 public:
-    QBmpHandler();
+    enum InternalFormat {
+        DibFormat,
+        BmpFormat
+    };
+
+    explicit QBmpHandler(InternalFormat fmt = BmpFormat);
     bool canRead() const;
     bool read(QImage *image);
     bool write(const QImage &image);
@@ -99,11 +109,16 @@ public:
 
 private:
     bool readHeader();
+    inline QByteArray formatName() const;
+
     enum State {
         Ready,
         ReadHeader,
         Error
     };
+
+    const InternalFormat m_format;
+
     State state;
     BMP_FILEHDR fileHeader;
     BMP_INFOHDR infoHeader;

src/gui/image/qimagereader.cpp

@@ -359,6 +359,8 @@ static QImageIOHandler *createReadHandlerHelper(QIODevice *device,
 #ifndef QT_NO_IMAGEFORMAT_BMP
         } else if (testFormat == "bmp") {
             handler = new QBmpHandler;
+        } else if (testFormat == "dib") {
+            handler = new QBmpHandler(QBmpHandler::DibFormat);
 #endif
 #ifndef QT_NO_IMAGEFORMAT_XPM
         } else if (testFormat == "xpm") {

src/gui/image/qimagewriter.cpp

@@ -201,6 +201,8 @@ static QImageIOHandler *createWriteHandlerHelper(QIODevice *device,
 #ifndef QT_NO_IMAGEFORMAT_BMP
         } else if (testFormat == "bmp") {
             handler = new QBmpHandler;
+        } else if (testFormat == "dib") {
+            handler = new QBmpHandler(QBmpHandler::DibFormat);
 #endif
 #ifndef QT_NO_IMAGEFORMAT_XPM
         } else if (testFormat == "xpm") {